Welcome!
Its a great thought to worry about keeping your batteries cool, but I haven't seen many posts here about it being a big problem. I have however seen many posts about mobile devices overheating and shutting down or lagging when flying in hot climates. Especially the older or underpowered devices. Of course there will always be posts saying, "I fly in 125F / 52C all day long with no problems!" Even so, my guess is that you'd run into a heat problem with your mobile device before you'd run into a battery problem.
Just something to keep in mind in the summer when the temps go up in your area.
[Note that I am not saying to disregard battery care. Please of course become familiar with best practices and make your choices accordingly]